Condensate pipe

The condensate pipe is a pipe through which a condensing boiler discharges waste water from the condensing process into the sewer. As metal pipework cannot be used, it is often easily identifiable as the only plastic pipe connected to the boiler.

Condensate pipe overview

Water vapour from the combustion process is channelled through the boiler (along with other gases from the combustion chamber) until so much heat is drawn out of it that it condenses back into water. (In a non-condensing boiler, this process is absent – the hot gases are simply expelled out of the flue and the heat is wasted.)

The condensate, i.e., the water produced from the condensation process, is collected in the condensate trap. Just like how the water in the U-bend of a sink stops bad smells from travelling up the sewer into the home, the condensate trap uses a portion of condensate water to prevent toxic fumes from being expelled into the sewer. A standard condensing boiler will produce 2-3 litres of condensate per hour of operation, although of course this figure may vary depending on the model and capacity of boiler. Per BS 6798, the provision must be made for this waste water to be discharged into either an internal soil stack or waste pipe, or into an external soil stack, gully, or soak-away.

In many boilers, the condensate trap contains a small siphon. Condensate is collected in the trap until it fills up to a level where the siphon is activated and the trap empties itself automatically. Condensate flows through the pipe in bursts of a few hundred millilitres at a time, which may be heard trickling through the pipe. The siphonic discharge of small amounts of water through the condensate pipe is preferable to a steady flow, as a constant drip is more liable to freeze. Plus, short bursts of warm condensate will thaw any ice that has started to form in the pipe.


The condensate pipe must be plastic – usually solvent-weld fittings – and at least 22 mm in diameter. Copper or steel pipework cannot be used. This is because, at a pH of 3-4, the condensate is slightly acidic, and metal-based piping would be more susceptible to corrosion.

Condensate pipes that are outside or run through an unheated outbuilding, such as a garage, must be insulated with waterproof lagging in order to prevent them from freezing and should not be longer than 3 metres. Where it is undesirable to insulate the pipe for aesthetic reasons, 32 mm external piping will greatly reduce the risk of freezing. The upsizing of 22 mm to 32 mm pipe should ideally be made within the property so that water cannot freeze in a 22 mm section that is outside or within a wall cavity.

The condensate pipe must have a fall of at least 1:100. This gradient is required in order to prevent waste water from other appliances connected to the sewer (such as a washing machine) inadvertently entering the boiler’s combustion chamber. The gradient should also prevent water from sitting in the pipe and possibly freezing.

The condensate pipe must also have as few bends as possible. This is in order to prevent the condensate from getting trapped in the pipe.


One of the most common condensate pipe problems is that the water freezes inside it, blocking the pipe. The boiler’s built-in sensors will detect that it cannot discharge the condensate, and will consequently prevent the boiler from lighting, leaving the household without heating or hot water. If a frozen condensate pipe is suspected, this can easily be remedied by pouring warm water on the exposed section of pipe, or by placing a hot water bottle on it. Click here to read more information on this topic, including how to prevent it from freezing in future.

Other obstructions in the condensate pipe may include sewage, which has travelled up the pipe due to a poorly configured waste water system in the building. In some very bad cases, the sewage may travel far back enough up the condensate pipe to overwhelm the boiler internally.

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Combi boiler pressure explained & how to fix it

The little pressure gauge on the front of your boiler may be small, but the information it tells you is the difference between your boiler working, or having no hot water or central heating. In this article, we’ll discuss exactly what combi boiler pressure means, and what can be done to fix it if your boiler has no pressure.

Combi boiler pressure explained

In order for a combi boiler to operate, the water in the central heating must be pressurised. While the exact amount of pressure required for a boiler may vary depending on model and manufacturer, most combi boiler systems need to be filled to a pressure of 1 to 1.5 bar when they are cold.

Water expands when it’s heated, and so the pressure rises when the boiler is on. Should the pressure get too high – 3 bar is usually the limit – the water will be discharged out of the system via the pressure release valve (PRV).

In a household with a combi boiler, there is no feed and expansion tank in the loft. Instead, the water inside the radiators is supplied directly from the mains. However, water regulations do not allow central heating systems to be directly connected to the mains permanently. That’s where the filling loop comes in. The filling loop is a small section of pipe on or near the boiler which provides a temporary connection to the mains. It may be a rigid pipe or a flexible one, like a shower hose. Opening up the valves on the filling loop allows you to top up your central heating system with water from the mains – which is normally at a pressure of 1 – 3 bar. Higher pressures may be reported.

How to fix low boiler pressure

Topping up the system with water in order to bring it to the correct pressure is a very easy task. Simply open the valves on the filling loop until the gauge displays the correct pressure. Be sure to close the filling loop swiftly once you’ve reached it.

Why does my boiler have low pressure?

The answer to this question is very simple: water is escaping from the central heating system. To put it simply, you have a leak. In some cases, it may be somewhere around the house; in others, the culprit is one of the boiler’s components.

If you find that you’re having to top up the boiler pressure often, then you can’t afford not to find the source of the leak and get it fixed. That’s because the water in your central heating contains (or should contain) inhibitor, which protects your radiators and boiler from internal corrosion. By frequently adding oxygen-rich water to your central heating system, you’ll encourage it to rust from the inside out.

Finding the leak

Check all the visible joints on your central heating pipework, and check the connections to your radiators to make sure that they aren’t weeping. Make sure that the radiator bleed valves are fully closed – you will need a radiator key to do this. If the radiators have been recently bled, the system may need topping up from the filling loop.

The pressure release valve

If there are no visible leaks around the home, then the leak may have something to do with the boiler itself. A common culprit is the pressure release valve. A faulty PRV will allow water to exit the system when it shouldn’t.

In the event of high pressure, excess water is discharged through the PRV and out of the building via the PRV release pipe. This pipe can be identified outside. It should not be confused with the condensate pipe, which is usually white, plastic, and connected to the drain or soil stack.

Check the PRV release pipe. Is it dripping? Check the inside with a piece of tissue to see if it is wet. If the PRV is leaking very gradually, then the water may be evaporating before you can spot it. Look at the brickwork of the building to see if it has been wet over a continued period of time. Signs of water may include residual lime scale and a change in the colour of the bricks.

You can also test to see if the PRV is discharging water by hooking a plastic bag over the end of the pipe, or placing a container underneath it to catch the water. Never block the pipe, as this could be dangerous.

Common pressure release valve faults include:

  • The valve has become defective and will no longer remain closed.
  • The washer inside the valve has perished, usually due to age.
  • The valve has become jammed open due to debris in the system – most likely oxides from internal corrosion.
  • The valve has become jammed open due to a faulty expansion vessel.

If the PRV is faulty, it will need to be replaced. If the PRV has been jammed open due to corrosion debris, the system will need to be powerflushed.

Faulty expansion vessel

Another component which may cause your boiler to lose pressure is the expansion vessel. On a combi boiler, this component is usually fitted inside the boiler’s casing. Its purpose is to accommodate the expansion of the water when it’s heated.

The expansion vessel consists of two internal compartments divided by a rubber diaphragm. One compartment contains water from the central heating; the other contains pressurised air. Air is much more easily compressible than water, and so when the water expands, the air is compressed.

If the air pressure inside the expansion vessel is too low, the system will have no way of accommodating the change in the water’s volume. Consequently, the water will discharge out of the system via the pressure release valve. Eventually, enough water will discharge from the system so that the boiler will report low pressure when cold, and won’t light.

The same problem can happen if the diaphragm in the expansion vessel is broken. The water will expand with nowhere to go, be discharged out of the PRV, and the boiler won’t have enough pressure to operate.

The expansion vessel is usually fitted with a Schrader valve. This is the kind of valve that’s found on car and bike tyres. A tyre pressure gauge can be used to check the pressure in the expansion vessel. If the pressure is too low (the optimum pressure is 1 bar or 15 psi), a foot pump or handheld pump can be used to add pressure. Water coming out of the Schrader valve is a good indication that the diaphragm inside the valve has a puncture. In this case, the expansion vessel will need to be replaced.

If it’s not the boiler…

If there is no evidence that the boiler and any of its components are faulty, then the leak is likely to be concealed, e.g., if pipes run under floorboards or within walls.


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16 Awesome Plumbing tips that can save you a fortune

While some aspects of plumbing can be tedious, there are some ways to make them a little bit more straightforward. There are also plumbing tips which may not only make a job easier, but potentially save your property from thousands of pounds worth of damage. Here’s a selection of useful plumbing tips we think are worth bearing in mind.

Plumbing tips

The most important of all plumbing tips…

Clockwise opens it, anti-clockwise closes it!


Use a magnet to check pipework for corrosion. Copper pipe is not magnetic, whereas any iron compounds that have formed inside a pipe will make the magnet stick.

The perfect pipe edge

When cutting a new piece of copper pipe with some pipecutters, cut a tiny piece off at the end. Instead of the flat, blunt edge, you’ll have a nice tapered edge – perfect for a compression fitting.

Save your copper scraps

…but don’t forget to save the piece you cut off! Take your old bits of copper to a scrap metal dealer – never throw it away! An old hot water cylinder may fetch anywhere up to £100.

PTFE threading

When using PTFE tape, always thread the tape in the opposite direction of the thread of screw. This will ensure that it stays in place and doesn’t unwrap when you do up the fitting.

Lead pipe smoothing

Got an old lead pipe you need to sand down? Heat up a stanley knife over a flame and cut it smooth – it’s much quicker and easier.

Immersion heater safety

Make sure your immersion heater thermostat is the new type, which cuts out when it fails. Older ones can fail in the on position, boiling the water in the hot water cylinder, and overwhelming the cold water storage cistern with boiling hot water. In such circumstances, an improperly supported cistern may split, scalding or even killing residents in bedrooms below.

Know where your stopcock is

In the event of a leak, you don’t want to be wasting time finding the stopcock while a leak is busy damaging your property. Take a moment to find it – it’s usually under or nearby the kitchen sink – and test that it works.

Know where your outside stopcock is

In the event that your inside stopcock is inaccessible, you can’t afford not to know where your external stopcock is. It’s usually in a small hatch in the pavement in front of your property. Most importantly, you will need a stopcock key in order to operate it – you can get a basic one from your local DIY store for less than a tenner. It’s absolutely worth it getting one: in the event of a burst water main behind the internal stopcock, if you can’t turn off the outside stopcock then you will simply have no way of turning off the water until the emergency plumber arrives.

Get a spare ball valve

While you’re in your DIY shop, pick up a spare ball valve – you can pick up a decent Part 2 valve for around a fiver, if that. Leave it in the loft, and in the event of a leaking overflow pipe, you should be able to fix the problem as soon as it occurs.

Put inhibitor in your central heating

You absolutely can’t afford not to inhibitor your central heating. Inhibitor is a chemical which stops oxidisation occurring – basically, it stops your radiators from rusting inside out. A bottle of radiator inhibitor costs around a tenner – the cost of replacing multiple radiators can cost hundreds or even thousands of pounds.

The power of vinegar against limescale

Vinegar is an effective descaler – use it to remove limescale stains in the bathroom or even for descaling the shower head. Make sure to use distilled white vinegar, as other types – malt or white wine – may leave stains.

Get your boiler serviced

Whether it’s a combi boiler, a system boiler, or a heat only boiler, get your boiler serviced, especially if you’re the one who paid for it to be installed. In addition to a standard one year warranty, many boilers come with an extended warranty that can last anywhere from 7 to 10 years as long as they have been installed by an accredited engineer. Missing out on an annual service could cost the boiler its warranty – and you a lot of money, if it breaks down later.

Protect your hot water cylinder when removing an immersion heater

When removing an immersion heater, leave as much water in the hot water cylinder as possible. Sometimes a lot of force is required to unscrew an immersion heater. By leaving a mass of water in the cylinder, this will help to prevent the cylinder from warping as you unscrew the heater from its boss.

Broken ball valve float? Here’s a temporary fix

Isolate the valve and unscrew the float from the float arm. Drain out the water inside, and put it in a freezer bag. Screw it back onto the arm of the valve and tie the bag in place. This will serve as a temporary fix before you get a replacement float.

Remember your lockshield turns

Whenever you have to close a lockshield valve on a radiator, e.g. for cleaning or replacing a radiator, make sure you remember how many times you had to turn the valve. The lockshield should be set to allow the right amount of hot water to pass through the radiator so that it heats up evenly. Remembering the number of turns will save you from having to balance the radiator.

So there you have it – 16 plumbing tips which may not only make your life easier but could save you a pretty penny in the long run. Be sure to bookmark this page as more will be added in future!

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Primatic cylinder

Primatic cylinder, alternatively a self-priming cylinderis a type of indirect hot water cylinder in which the water for the central heating is separated from the domestic hot water by an air lock inside the heat exchanger. This is in contrast to a standard indirect cylinder, in which the heat exchanger is typically a coil of copper pipe.

Primatic cylinders are supplied by the cold water storage cistern in the loft. Their design means that a separate feed and expansion tank is not necessary. However, they come with several disadvantages that make them inferior to standard indirect cylinders.

Primatic cylinder overview

In a primatic cylinder, the heat exchanger also facilitates the supply of water for the primary circuit, i.e. the central heating. When the cylinder is filled, water flows through the heat exchanger allowing water to pass into the primary circuit. As the cylinder fills, the shape of the heat exchanger traps air inside itself – imagine holding a bowl upside-down at the bottom of the kitchen sink, and turning on the taps. This is the priming of the cylinder – the formation of the bubble.

When the cylinder is full and the boiler is activated by the cylinder thermostat, hot water from the boiler flows through the heat exchanger. Heat is transferred by the heat exchanger to the rest of the water in the cylinder, providing hot water for the taps in the home. An immersion heater will usually be fitted so that the household will still have hot water even in the event that the boiler isn’t working.

A pipe rising up from the heat exchanger and bending down in the shape of a sharp loop allows any air or gases which form in the primary circuit to discharge into the cylinder. The gases will then rise up and out of the hot water cylinder, and out of the expansion pipe in the loft.

Since both hot water cylinder and central heating system are supplied with water by the cold water storage cistern in the loft, there is no need for a separate feed and expansion tank and its associated pipework. The expansion of the water in the primary circuit when it’s heated by the boiler is also accommodated by the heat exchanger – the bubble is compressed and changes position.

If you want to know why you have a cold water storage cistern, a hot water cylinder, and a boiler, but no feed and expansion tank or expansion vessel, then it’s quite possible that you have a primatic cylinder. It is also possible to buy primatic fortic cylinders, i.e. fortic cylinders with their own integrated cold water storage cistern. These remove the need for loft cisterns altogether, although they are not frequently encountered.


In terms of construction, a primatic cylinder is similar in many respects to a conventional indirect hot water cylinder. Both are generally made out of copper, with a layer of foam insulation. Older cylinders may have a separate insulation jacket, which is tied around the cylinder. The top of the cylinder is bell-shaped to prevent air locks, and the bottom of the cylinder will usually be concave to improve its structural integrity. The cylinder should be situated on a flat, stable, continuous wooden base – ideally ¾ inch plywood across three timber bearers. Air gaps between the timber bearers will permit the circulation of air under the cylinder, limiting the formation of condensation.


While primatic cylinders remove the need for a separate feed and expansion tank in the loft, they come with several significant disadvantages. The main disadvantage is that any loss of the air bubble will cause the domestic hot water for the taps and the bath to merge with the murky stale water inside the radiators. An obvious indication that the two bodies of water have merged will be brown-tinged water coming from the hot taps – hardly the ideal sort of water for doing the washing up. The only way to correct this problem is to drain the cylinder down and fill it up carefully, allowing the air bubble to form again and hoping that it stays in place.

The possibility for these two waters to merge also means that one cannot put any inhibitor chemicals inside the primary circuit in order to protect the system. As a result, the radiators and the boiler are much more liable to corrosion damage and blocking, which may prove expensive. Also, it is not possible to fit a shower pump on a system with a primatic cylinder, as this may cause the loss of the airlock and the merging of the two waters.

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Combi boiler

combination boiler, or combi boiler as it is typically known, is a boiler which provides the heat for both the radiators and the domestic hot water outlets in the home. Combi boilers are the most common type of boiler in the UK, accounting for around 70% of central heating system configurations in British households.

The most distinguishing aspect of a combi boiler is that it eliminates the need for a hot water cylinder and for water cisterns in the loft space. This is because the water for the central heating is supplied via a temporary connection to the mains, instead of a feed and expansion tank. As for the hot water for the taps, there is no need for a boiler to heat water in a hot water cylinder – a combi boiler heats water from the mains on demand. Without the need for a hot water cylinder, there is consequently no need for a cold water storage cistern.

Combi boilers are fuelled by natural gas or oil. Common manufacturers include Ideal, Vaillant, Vokera, Potterton, Baxi, Glow-worm and Worcester Bosch. Gas combi boilers are usually wall-mountable, while oil-fuelled ones are often free-standing. It is illegal for an engineer or indeed any individual who is not on the Gas Safe Register to work on a gas-fuelled combi boiler.

Combi boiler history

The combi boiler was invented in the 1960s by Vaillant, the German heating, cooling and engineering giants based in Remscheid, Germany. Despite their ground-breaking invention, there was little reason to even import combi boilers to Britain, as UK water regulations did not permit either domestic hot water or central heating systems to be directly connected to the mains – hence the use of tanks in the loft.

However, combi boilers got a huge leg up in the British market in the 1980s, when water regulations changed to allow central heating systems to be filled up via a temporary connection to the mains.

How does a combi boiler work?


When the thermostat detects that the temperature in the home has fallen below a predetermined level, the boiler’s circuitry sends a signal to open an internal gas valve and for the electronic ignitor to light the burner inside the combustion chamber. Heat generated in the combustion chamber is transferred to the water flowing through the primary heat exchanger. This hot water is pushed through the radiators by the pump, and the gases generated from the combustion process are expelled through the flue. Heat from the hot water is emitted into the home via the radiators, and the cooler water returns to the boiler before being heated again and redistributed by the pump, until the temperature in the home has reached the desired level and the thermostat ceases to request heat from the boiler.

Hot water

When a hot tap is opened, a sensor detects the movement of water through the pipe and lights the burner. Water from the central heating circuit is heated by the primary heat exchanger. This water is then pumped through a secondary heat exchanger. Here, heat from the primary circuit is transferred to cold mains water, which then goes on its way to the outlet that has been opened.

If a hot outlet is opened while the central heating is already activated, a combi boiler will always give priority to the hot outlet. A diverter valve controls whether water heated by the primary heat exchanger should flow through the radiators or through the secondary heat exchanger.

It is important to note that the two bodies of water – the domestic hot water and the water in the central heating – never come into contact with each other. The stale, recirculated water of the central heating will (or should) contain anti-corrosion chemicals which would contaminate the hot water.

Condensing boiler

When hydrogen gas is burned (oxidised) during the combustion process, water vapour, i.e. steam is formed. A condensing boiler condenses this steam back into a liquid, thus recovering the heat energy which would otherwise be lost. This increases their energy efficiency. The condensate, i.e., the water, is collected in the condensate trap before being discharged into the sewer by the condensate pipe. Like how the trap of a sink carries a small amount of water to block bad smells from travelling up drain, the condensate trap holds a small body of water so that any toxic gases produced by the boiler cannot travel down the condensate pipe.

Consequently, a condensing boiler is not a special type of boiler in itself; rather, condensing is a characteristic, and is an extremely common characteristic of combi boilers. In fact, the term “condensing boiler” is becoming more and more of a misnomer, as all boilers installed in the UK after 2005 must have this feature for environmental reasons.

Other components

Other important combi boiler components include the following:

  • Pressure Release Valve or PRV. The water inside the central heating should be set to approximately 1 – 1.5 bar when cold. Should the pressure in the system rise above a predetermined level (e.g., 3 bar), water will exit the system through this valve.
  • Venturi. This is a valve which controls the flow of air into the combustion chamber to ensure the correct ratio of air to gas, and consequently, to ensure the clean and complete combustion of the fuel.
  • Thermistor. The word is a portmanteu of ‘thermal’ and ‘resistor’. As the name suggests, thermistors control the flow of electrical current in a circuit based on the temperature they detect.
  • Expansion vessel. Easily identifiable by its red exterior, the expansion vessel accommodates the increase in volume of the water when it is heated. Hot water should never be contained without allowing for this, as it may have explosive results.
  • Filling loop. This is a length of pipework with a valve at each end that, when opened, is used to fill up the central heating circuit with water from the mains. It must also contain a non-return valve so that water in the central heating cannot flow back into the mains and contaminate it. The filling loop may be a short length of rigid copper pipe, or a flexible braided hose.

Combi boiler pipes

A combi boiler will have the following pipes connected to it:

Flow & Return

These two 22 mm copper pipes carry water to and from the radiators. Hot water is distributed to the radiators via the flow, and the heat it contains is emitted by the radiators. The cooler water returns to the boiler via the return, after which it is brought back up to the target temperature by the boiler, and pumped through the radiators again.

Cold main

A combi boiler gets its water supply from a 15 mm copper pipe fitted to the mains in the property.

Filling loop

Depending on the make and model of the boiler, the filling loop may be a piece of rigid pipework, or it may be a flexible braided hose. Its purpose is to provide a temporary connection to the mains in order to fill the central heating with water. This is necessary because, as mentioned, a permanent connection to the mains is not permitted by water regulations.

The filling loop is normally connected to the central heating side via the return pipe, although on some boilers it may be connected to the flow. A non-return valve must be fitted so that water from the central heating can never flow back into the mains.

Gas supply pipe

The intake for supplying the boiler with gas on the boiler itself is normally 15 mm. However, the actual supply pipe itself is likely to be wider; 22 mm or even 28 mm, depending on a number of factors, such as the power of the boiler, its distance from the gas main, and the number of bends in the pipework. When installing a combi boiler, the engineer must calculate the correct diameters so that the boiler is not undersupplied with gas.

Hot outlet

Hot water for the taps is distributed to the house via this pipe. It is usually 15 mm copper.

PRV pipe

Should the water in the central heating system exceed a set pressure (usually 3 bar), this will be discharged by the pressure release valve through a 15 mm copper pipe outside the property.

Condensate pipe

Waste water from the condensation process is discharged into the sewer via the condensate pipe, which is usually 22 mm plastic solvent weld. On the outside of the property, the diameter may increase to 32 mm or even larger. The purpose of the increase is to prevent any water in the pipe from freezing, which would block the pipe and disable the boiler.

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Fortic cylinder

A Fortic cylinder or Fortic hot water tank; alternatively, a combination cylinder, is a vessel designed for heating and storing hot water in the home. It is typically made out of copper and covered in a layer of foam insulation.

Unlike a standard vented hot water cylinder, a Fortic cylinder has its own integrated cold water storage cistern. This is in contrast to a standard vented cylinder, which is typically supplied with cold water from a 25 – 50 gallon cistern in the loft.

The cistern section of a Fortic tank is located directly above the hot water cylinder and fulfils exactly the same purposes of a conventional cold water cistern: to replenish the cylinder with cold water, and to accommodate the expansion of the water as it is heated.

Fortic cylinder overview

Since a Fortic cylinder has its own integrated storage cistern, it will typically be supplied by a 15 mm compression fitting from the mains. The water level inside the cistern is controlled by a ball valve; ideally a Part 2 ball valve. An overflow pipe must also be fitted, When the cistern is full, the water level should be at least 25 mm below the bottom of the overflow pipe. A Fortic cylinder should also come with a close-fitting lid to prevent the ingestion of dirt and debris in the cistern.


Water does not flow directly into the top of the hot cylinder from a hole in the bottom of the cold cistern, because hot water rises. Were this to happen, then the cold cistern would contain the hottest water. Instead, cold water is delivered to the cylinder via a pipe which runs from the base of the cistern to the base of the cylinder. This pipe is often partly visible underneath the insulation, running down the length of the cylinder.


Another pipe runs from the top of the cylinder to the top of the cold water cistern, higher than both the ball valve and the overflow. This is the expansion pipe, which accommodates the expansion of the water as it’s heated, and allows it to vent into the cistern if necessary. Hot water should never be contained without accommodating its expansion, as this would be dangerous.


In some Fortic cylinders, there may be a galvanic/sacrificial anode in both the cylinder and the cold cistern. This is a piece of metal which is more certain to corrode than copper, thus preventing the cylinder from corrosion. In the cold cistern, the anode may be contained in a small piece of copper or plastic pipe attached to the bottom.

Fortic cylinder types

Fortic cylinders are available in numerous different arrangements. They are available as both direct and indirect cylinders. In a direct Fortic cylinder, the water is heated via two immersion heaters: one situated near the bottom, and one about two thirds up. The lower immersion heater will typically operate on a cheaper, night electricity tariff (Economy 7). The top one uses more expensive, day-time electricity to boost the temperature of the water as it is consumed during the day. The Economy 7 immersion heater works during the night to heat up the water for the day ahead.

In an indirect Fortic cylinder, the water is heated by a heat exchanger. The heat exchanger is normally in the form of a coil of copper pipe, which carries hot water from the boiler. Water enters the top of the coil via the “flow”, and exits at the bottom by the “return”. These are typically 22 mm fittings.

It is possible to buy primatic Fortic cylinders. These are cylinders whose heat exchanger also facilitates the supply of water to the central heating circuit, eliminating the need for a separate feed and expansion tank. The two bodies of water are separated via an air bubble which forms inside the heat exchanger. However, not only are primatic Fortic cylinders few and far between, they have serious disadvantages – the main one being that they are much more liable to corrosion. This is because inhibitors cannot be added to the radiators.

Pros & cons

The main benefit of a Fortic cylinder is that there is no need to install a separate cold water storage cistern. For this reason, Fortic cylinders are commonly installed in flats and properties without loft space. A direct Fortic cylinder is an effective solution for providing hot water in a property with no loft or gas supply, i.e., there is no space for cold water cistern and no gas for a combi boiler.

However, Fortic cylinders do have their drawbacks. Flow rates at hot outlets will be poorer than systems with a separate loft cistern due to the lower pressure head, and even poorer than combi boiler and pressurised cylinder systems. They are also generally incompatible with pumped showers, as most shower pumps and digital showers require a cold storage capacity of 50 gallons (227 litres) as standard. Even the biggest Fortic cylinder, with a height of 180 cm, will only have a cold cistern capacity of around 40 litres. Finally, there will always be the potential annoyance of the sound of running water within the living area of the property when the cistern fills.

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How to unblock a toilet fast

A blocked toilet is one of the most common plumbing problems in the home. In this article, we’ll tell you everything you need to know about how to unblock a toilet if the water won’t go down the pan.

In 2016, the drain unblocking organisation Welsh Water told the BBC that the drain network is being used like a bin. The UK in fact spends tens of millions of pounds on drain unblocking services every year. Hopefully you won’t have to add to that statistic – here’s how to unclog a toilet, without – fingers crossed – having to get an emergency plumber.

How to unblock a toilet – flushing overview

When you flush the toilet, water flows from the cistern into the pan. The pan contains a bend or trap, which keeps a small body of water present. This acts as a barrier between your bathroom and the sewer, keeping bad smells from the drain out of your house. The shape of the trap also creates a siphon effect, helping to suck the effluent out of the pan. Most toilet blockages are located inside the pan, i.e., the porcelain component.

Tips and equipment for unblocking a toilet

There’s a few things you should think about before beginning this job, which will hopefully make it as bearable as possible.

  • Rubber gloves – These are pretty much the cardinal piece of equipment for this task. They’ll stop your hands from getting dirty. Plus, if you know what it is that’s blocking your toilet, such a nappy or toy, you can use them to simply reach in and grab it.
  • Ventilation – Make sure the area is well ventilated. Open the bathroom window to let plenty of fresh air in. Don’t forget, however, to close certain doors. Bad smells will travel throughout the house.
  • Old newspaper or towels – Newspaper is a cheap way of soaking up any accidental spills and can be disposed of easily (but don’t throw it down the toilet!) Towels can be used as something more robust, but you may wish to throw them away afterwards.
  • Old clothes – Depending on the severity of the blockage, you way want to don some clothes which you don’t mind getting dirty.
  • Hot water – Some of these strategies involve the use of hot water, so be careful not to scald yourself.
  • Chemicals – Some of these strategies involve the use of chemicals. Always read the label, and never mix chemicals. This could result in a dangerous chemical reaction.

Before we begin, don’t be tempted to keep flushing – especially if the pan is full close to the brim, and there is no sign of the contents disappearing. You may end up with very wet feet and a lot of regret!

How to unblock a toilet with a plunger

In order to unblock a toilet with a plunger, you’ll need one specifically designed for this purpose. Toilet plungers have an extension on the cup which ensures they form a good seal in the pan. A plunger without this cup – known as a sink plunger or a cup plunger – is intended for unblocking sinks, showers and baths.

  1. Make sure there’s water in the pan. For argument’s sake, we’ll assume that there is. However, if the water has drained away very slowly, you’ll need to top it up again. Pour some water in but don’t flush it. This is to ensure that the plunger cup is covered, and to prevent the ingestion of air.
  2. Place the plunger in the water. You should do this in such a way so that there as little air in the plunger as possible. That’s because you want to make sure the plunger is agitating the water. Any air inside will act as a cushion for the water and stop its movement from shifting the obstruction.
  3. Place the plunger over the hole. Make sure that it forms a seal over the hole. If this is difficult, try dousing the cup of the plunger in hot water. This should make it more malleable.
  4. Plunge carefully at first. Don’t be tempted to plunge as hard as you can at first. Any air inside the cup may cause a splash.
  5. Plunge! A combination of small, sharp plunges and forceful, vigorous ones should get the water moving and the blockage on its way out.
  6. Be patient. You may not get immediate results.

If it works, congratulations! You have successfully unblocked a toilet with a plunger.

How to unblock a toilet without a plunger

If you didn’t have any luck with a plunger, or you simply don’t have one, there are still loads of different ways to unblock your toilet. For starters, you can try it with the toilet brush. It won’t be as effective a good plunger, but it may be enough by itself to agitate the water to clear the blockage.

How to unblock a toilet with hot water

This method is best used when a toilet is partially blocked, as pouring water into a toilet that’s completely blocked will probably just make the pan overflow.

  1. Fill up a bucket with hot water from the sink or the bath. Never use boiling hot water from the kettle, as sudden changes in temperature can crack porcelain.
  2. Pour the water into pan. You’ll need to pour the water as hard as you can without making the pan overflow. The higher the point from which you can do this, the better. In theory, the force of the large volume of water should shift the obstruction. The warmth of the water may also help to loosen any fats that are causing the blockage.

How to unblock a toilet with a mop

You can use a mop and plastic bag in order to unblock a toilet. This method works roughly the same way as a plunger, by agitating the water. You should ideally have three or four carrier bags to do this method as cleanly as possible.

  1. Place a carrier bag over the mop head. Use the handles of the bag to tie it in place; alternatively, hold it in place with your other hand.
  2. Place the mop and bag in the water.
  3. Use sharp, brisk strokes to push water down the hole. The movement of water should move the blockage. Once again, be patient – it may take a dozen or two strokes before you get results. Don’t do it so hard that the bag breaks – you don’t want to be adding to the blockage.
  4. Let the bag drain. Once you’ve unblocked the toilet, let the bag drain. Most carrier bags, such as the ones you get in supermarkets, tend to have one or two small holes in the bottom. The bag will probably have filled up with some of the contents of the toilet.
  5. Dispose of the bag. Once it has drained, you can place one or two more carrier bags over it in order to take it off the mop head as hygienically as possible.
  6. Disinfect the mop.

How to unblock a toilet with caustic soda

Otherwise known by its chemical name of sodium hydroxide, caustic soda can be an extremely effective toilet unblocker. It is the active ingredient in many sink and drain unblockers, and is cheaply available from local DIY stores. It works using a combination of heat and chemistry. Mixing caustic soda water creates heat, which softens grease and fatty deposits. The caustic soda itself converts fat into glycerine and salts, which are water soluble and can be flushed away. This method assumes that the pan is empty but the toilet is blocked (i.e. the water is draining away very slowly).

  1. Health and safety. Caustic soda can be exceedingly dangerous if not used correctly. When unblocking a toilet with caustic soda, you should wear chemical-resistant gloves and eye protection, and mouth/nose protection to stop you from inhaling the fumes. Make sure the area in which you are working is well ventilated.
  2. Prepare the mixture. Slowly add approximately 1 kg (2.2 lb) of caustic soda to approximately 4.5 litres (1 gallon) of water in a bucket. The mixture will bubble and fume. Keep your face away from the fumes, taking care not to inhale them. Tip: Always add caustic soda, never the other way round. Adding water to caustic soda will create an extremely high amount of heat. Never pour caustic soda crystals straight into the pan – the crystals will solidify and make the blockage worse.
  3. Slowly pour the mixture into the pan.
  4. Put the toilet seat down.
  5. Leave it overnight, or as long as stated by the instructions.
  6. The next morning, pour one or two buckets of hot water down the toilet. The toilet should now hopefully be unblocked.

How to unblock a toilet with a clothes hanger

It is possible to unblock a toilet with a clothes hanger/coat hanger. A basic wire clothes hanger can be bent into the appropriate shape, however you should be verycareful not to scratch the porcelain of the pan.

  1. Bend the clothes hanger. Twist it out of its original shape until it is roughly straight. While leaving around a third of it to be used as a handle, bend the remaining two thirds into a curve which can be inserted into the hole. Bend the business end over itself in order to make it more rigid.
  2. Insert the wire into the hole. While following the shape of the bend, push your way forward to try to clear the path. Take care not to scratch the pan.


One of the most important things you can do to prevent a blocked toilet is to educate household members what shouldn’t go down the toilet, such as wet wipes, dental floss, tampons and condoms. These things should be carefully disposed of with general household waste, and never flushed down the loo. Putting a basic bathroom bin next to the toilet should eliminate the temptation to flush these things. You should also make sure that younger family members know not to put random objects and toys in the loo.

There are certain chemicals, such a paint, which should never be flushed down the toilet or even thrown away in the rubbish. Instead, you should take these to your local waste disposal facility. Some compounds, such as grease and wax, may solidify and create a blockage. Unwanted medicines and medical items should be taken to your pharmacist, GP or hospital; used syringes and needles should be placed in a medical sharps box.

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British taps: here’s why the hot & cold are separate

Ah, British taps. For most Brits, separate hot and cold taps (or faucets, if you’re visiting from the good old US of A) are a part of every day life. However, for many visitors to the UK, including those from continental Europe as well as America, they are simply baffling. Why on earth are they separate? How can you wash your hands comfortably in water that’s either scalding hot, or ice cold? In this article, we’ll go through the most common arguments.

1. British taps risk contaminating the mains

One of the most widespread explanations refers to the construction of British houses after the Second World War. British houses built after this period were typically equipped with a cold water storage cistern in the attic. One of the main purposes of this cistern is to supply the hot water cylinder.

Nowadays, such cisterns are subject to a number of strict regulations in order to protect the water from contamination. For example, they need to have a lid in order to prevent debris and rodents from getting inside, and they must have certain fittings which prevent the ingestion of insects (which could otherwise find their way inside via travelling up the overflow pipe).

However, these regulations weren’t always in place. Older cisterns often didn’t have a lid, and they were usually made out of galvanised steel, which would corrode. Insects, rodents and even errant birds in the loft space would occasionally find their way into the tank, drown, and contaminate the water – which would eventually be used as hot water for the taps. That’s why, in British homes, your family told you not to drink from the hot taps or the bathroom taps.

It is this risk of contamination which is frequently cited as the reason why British taps are separate. It is argued that, in mixer taps, the hot water – which cannot be guaranteed as safe to drink – would merge with cold water from the mains and contaminate it.

Flaws – the taps

However, there are a number of flaws with this argument. The cold water storage cistern usually supplies the cold water to the bathroom outlets as well as the hot. Thus, there wouldn’t be any contamination of the mains water when both hot and cold come from somewhere else.

Another reason against this explanation is the taps themselves. Many mixer taps have separate internal waterways, meaning that the hot and cold waters never come into contact with each other until they exit the tap, so there’s no chance they can mix. As for mixer taps which do blend the hot and cold water inside the tap body, they require non-return valves to be fitted to both the hot and cold supply pipes. Either way, there’s no chance for contamination of the mains.

The water pressure

The other argument against this explanation is the pressure difference between the hot and cold water. Cold water from the mains is at a much higher pressure than water from the hot water cylinder, which relies on gravity.

It is theoretically possible in a faulty mixer tap or a mixer tap without any non-return valves for hot water to be drawn back into the mains. However, what often happens in this situation is that the high pressure cold water displaces the low pressure hot water, and fills up the cold water cistern from its outlet pipe at the bottom. It’s a common complaint from residents who, after installing a new mixer valve, find that their cold water cistern overflows when they run the bath or take a shower. In other words, the hot and cold water should never be allowed to mix with the chance of the hot water flowing back into the mains regardless of possible contamination. That’s because when it does, it tends to make the cold water cistern overflow.

So while this argument has a logical premise, it doesn’t really stand up to scrutiny.

2. Tradition

So why are British taps separate then? The simplest explanation is probably the best one: tradition. Most British housing was built at least a hundred years ago. In fact, many properties are even older. This was a time when there was no running hot water, and certainly no central heating. Mixing valves didn’t exist, and there was no reason for them anyway: any taps or spouts were cold only. The only way to get hot water was to heat it in a pan or a kettle over a fire. Consequently, when domestic hot water systems were invented, they were added separately. Houses which were rebuilt after the war carried on this tradition.

So what about, for example, Germany, a country where mixer taps are in practically every bathroom? German houses don’t have cold water storage cisterns  – all taps including the hot ones are supplied by a mains-fed tank. This means that there is equal pressure on both hot and cold, so no chance of creating an overflowing water tank.

But perhaps the reason why German plumbers took so strongly to mixer taps may be because of the sheer destruction of German housing stock during the Second World War. After the war, one in five buildings were destroyed. In many cities, not a single house was spared. Thus, there came the opportunity not to carry on a tradition, but to start a new one.

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Fortic & Primatic cylinders: what’s the difference?

The hot water cylinder is one of the most important components in your home. Hot water cylinders come in different types as well as in different sizes. But what’s the difference between a fortic tank and a primatic tank?

The difference between these two tanks relate to two different design aspects. Two things they do have in common, though, is that they are both vented and low pressure. By vented, these means that they are open to atmospheric pressure. And by low pressure, this means that they are supplied by a storage cistern.

But what makes a fortic tank unique is that unlike a conventional hot water cylinder, a fortic tank has its own integrated cold water storage cistern, instead of having a separate cold water storage cistern in the loft.

Fortic cylinders are ideal for flats or smaller properties where it wouldn’t be practical or possible to install a bulky cold water storage cistern. You can also buy both direct and indirect fortic cylinders.

  • An indirect fortic cylinder contains an internal heat exchanger, which consists of a coil of copper pipework. Water heated by the boiler from the central heating circuit is pumped through this coil, heating the water in the cylinder indirectly.
  • A direct fortic cylinder does not contain a coil. The water is instead directly heated by two immersion heaters. One of these heaters is typically on a cheaper night tariff of electricity (Economy 7); the other is used as a heat boost during the day.

So, what’s a primatic cylinder? The answer lies in the heat exchanger. You see, in a typical indirect hot water cylinder – fortic or not – the heat exchanger consists of this coil of copper pipework we mentioned in earlier. Water in the coil and your radiators is supplied by a feed and expansion tank in the loft.

However, in a primatic cylinder, the cold water storage cistern not only supplies the cold water to be heated for the taps, it also supplies the water for your central heating. When the cylinder fills up, an air bubble is formed inside the heat exchanger. It is this air bubble which keeps the domestic hot water and the central heating water separate.

For this reason, primatic cylinders have serious disadvantages in comparison to cylinders with a coil and a feed and expansion tank in the loft. You can’t fit a shower pump to them, and most importantly, you can’t put any inhibitor chemicals inside the central heating in case the bubble is lost and the two bodies of water merge. The end result of the latter is rusty brown radiator water coming out of your hot taps, and shorter radiator life, since you can’t put any chemicals inside them to stop them from corroding.

So there you have it – that’s the difference between a fortic tank and a primatic tank. There is actually quite a lot of difference, albeit in very different respects. It’s actually possible to purchase hot water cylinders which are both fortic and primatic, although these are very expensive and much less frequently encountered.

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Emergency plumber: what to do & who to call

Need an emergency plumber? Whichever corner of the country you’re in – London, Manchester, Cornwall or Edinburgh – this handy guide will tell you how to find a 24/7 plumber, who to contact, and how to quickly stop a leak or a burst pipe before they arrive to fix it.

Contents – Emergency plumber

How to quickly stop a burst pipe or a leak

An emergency plumber can take anywhere from 30 minutes to a couple of hours to attend your property. If you’ve got a leak or a burst pipe spraying water everywhere in the house, you can still stop the problem from getting worse. The first thing to do is find your stopcock or stop tap. This is a valve which controls the supply of water to every outlet in your home. It’s usually made out of brass and looks a bit like a tap, except with a pipe at each end. You’ll normally find it under the kitchen sink. It can also be found on the mains pipe which rises all the way up into the loft. This pipe is known as the rising main, and supplies the cold water storage cistern.

Can’t find the stopcock near the kitchen sink? It may be in another cupboard, a pantry, or in a different room altogether. It may be under the floorboards in some older properties. In some cases, it may have been boarded over by a lazy kitchen fitter when installing a new kitchen. In communal accommodation such as flats, it may be in a cupboard in a shared hallway. Such a cupboard may also contain the stopcocks for other flats or apartments in the building.

To turn off the water, turn the handle of the stopcock clockwise until it stops. This will prevent the leak from continuing indefinitely.

If the water won’t stop

Shutting off the stopcock won’t stop the leak immediately. At the very least, there will still be residual water in the pipes. You can limit the amount of water that drains out through the leak by opening the kitchen cold tap.

Leaking radiator or leaking radiator pipe

If you’ve turned off the stopcock and the leak doesn’t subside at all, it’s because it isn’t directly on the mains pipework. If you have a combi boiler and a burst radiator or burst radiator pipe, the leak will continue until the radiator and any adjacent pipework are empty. Potentially, the entire contents of the central heating circuit may leak out – i.e, the water in every radiator.

If you don’t have a combi boiler, then the water in your radiators is probably supplied by a feed and expansion cistern. This is a small cistern in the loft which supplies the radiators with water. Turning off the mains will stop the cistern from filling, and the flow of water from the leak should eventually stop. However, once again, potentially the contents of all the radiators may leak out until it does.

Cold water pipe leaking

If you’ve turned off the mains but the leak is from a cold pipe and it won’t stop, this may be because of the cold water storage cistern in the loft. Even with the mains off, this cistern may still contain up to 50 gallons of water. You can stop this water from exiting via the leak by turning off the gate valve on the cold outlet pipe. This is usually situated close to the cistern in the loft. If you can’t access the loft, opening all the hot taps will empty the cold water cistern. Opening the cold taps in the bathroom will help drain it faster, unless they are fed by the mains.

Hot water pipe leaking

If you’ve turned off the mains but the leak is from a hot water pipe which isn’t part of your central heating – and isn’t slowing down, then this is once again due to the water remaining in the cold water storage cistern. Hot water leaves your hot water cylinder courtesy of gravity acting on the water in the cold storage cistern.

You can immediately stop a hot water pipe leak from getting worse by closing the gate valve on the cold supply pipe to the hot water cylinder. This is easily identifiable by a red wheel-shaped handle in your airing cupboard, on a pipe which is usually the lowest one connecting to the cylinder.

If this doesn’t work, then opening all the hot taps is guaranteed to empty the cistern. Opening the cold taps in the bathroom will help empty the cistern faster, unless once again, they are fed by the mains.

Before calling an emergency plumber – do you actually need one?

This is probably the most important question – is an emergency plumber actually necessary? Take for example, an overflowing toilet cistern. The toilet at this author’s home was once overflowing. Water was pouring out of the overflow pipe at the side of the house. A quick check in the cistern showed that the float had merely unscrewed itself from the arm of the ball valve. Simply screwing the ball valve back on the float arm solved the problem in a matter of seconds.

Of course, more complex and more serious problems may require an expert. Even if you have stopped the problem from getting worse, you may not have the time or the tools to fix it. And even if you can fix it yourself, it may be much more straightforward to get a professional to do it. Also, fixing it yourself may not necessarily save you money. For example, you may find yourself having to take unpaid time off work to deal with it.

At any rate, if you feel that your skills aren’t up to scratch or that you can’t diagnose the problem yourself, you are much better off calling an emergency plumber. And remember, there are some things which should only be done by qualified professionals, such as removing asbestos or working on gas appliances.

Work out who you’re going to call

Finding an emergency plumber can be very tricky. If you have time, ask family and friends for recommendations. Thanks to word of mouth advertising, a reliable plumber will never be short of work.

Emergency plumbers online

If this route doesn’t come up with any names, the next step is to search online. The Association of Plumbers and Heating Contractors (APHC) and CIPHE, the Chartered Institute of Plumbing and Heating Engineering, are trade bodies for the UK plumbing and heating industry, and they maintain a list of registered plumbers. You can check if there’s anyone local to you by entering your postcode.

An obvious port of call is the Yellow Pages, which you can find online as However, while the site encourages customer reviews, it is simply a business directory, and doesn’t do much by itself to vouch for a tradesman’s credentials.

Verification sites

The independent UK consumer magazine Which? has a “Trusted Trader” scheme which scrutinises tradesmen and endorses them with its logo if they pass their assessment. Another good place to turn is, which is an index of tradesmen vetted and monitored by the site. It also encourages consumers to leave a review of the contractor they have hired. It goes without saying that for an emergency boiler work, you need someone who is on the Gas Safe Register. You should keep an eye out for credentials provided by boiler makers themselves. That’s because some of them operate their own accreditation scheme.

Once you’ve got some possible names to call, do a bit of extra research, if your circumstances allow. Do they have a website or a Facebook page? While not every good plumber has the time to maintain a presence on social media (or the need, due to work via word of mouth), a plumber who takes pride in his work may share some photos of his recent projects, accompanied by positive reviews. You should also keep a close eye out for the reviews which the plumber would prefer that you didn’t read.

Write down the task

Before calling an emergency plumber, it’s a good idea to write down as much as you can about the problem. This will prevent you from forgetting anything on the phone. It will also help the plumber to prepare for the task effectively. Don’t forget to mention how long the problem has gone on for, as well as anything you have attempted in order to fix it.


If possible, it’s definitely worthwhile doing a bit of research before hiring an emergency plumber to tackle the issue. For example, if your old gravity-fed shower has stopped working, there are several modern replacement solutions available. While a good plumber will talk you through the different options and explain what is and isn’t possible based on your individual system, it is a good idea to enter this conversation with an idea of what you are looking for. The clearer your end goal is, the better the plumber will know how to meet your expectations.

Make the call

Once you’ve done these things, it’s time to start calling. Explain the issue and how you would like it to be resolved. While an emergency plumber may be able to give you a rough idea as to how much it will cost, he probably won’t be able to give you an exact price until he has seen for himself what is required. However, he will be able give you his hourly rate and initial call-out charge, and also an estimate as to the cost of parts and equipment. Plumbers also sometimes have set prices for certain tasks.

You should find out if the plumber has insurance, and if that insurance covers adjacent properties, such as your neighbours. You should also find out if the plumber guarantees their work, and if their guarantee is backed up with insurance. An insurance-backed guarantee means that their work is still covered, even if they go bust. Also, don’t forget to ask if they are a member of the aforementioned trade bodies.

Calling emergency plumbers

You should contact and compare at least three or four different plumbers. Ideally, you want them to come round and give you an exact quote. Of course, in an emergency, this probably isn’t possible. However, it’s important to do as much as you can to obtain a competitive price. That’s because there is no standard industry rate for plumbers. Also, try not to rush into anything. A good emergency plumber will understand that you may need a bit of time to think things through. You may also need to discuss things with other members of the household.

Getting the work done

Once you know which plumber to hire, you should make an agreement in writing as to what you are expecting. This agreement should ideally be in the form of a written contract. It should contain a clear description of the project, the agreed price (most likely the initial quote) and the rate. (For longer projects, this should also contain the start and finish dates.)

You should also agree on the payment method beforehand. You do not want to try to pay for the work on a credit or debit card only to find out that the plumber only accepts payment by bank transfer. Once the work has been completed, this could put both parties in an awkward situation, depending on your finances.

When the work has been completed, don’t forget to ask for a Work Completed Certificate. This may be necessary in order to demonstrate that the work complies with local building regulations. Good luck, and get ready to put the kettle on and get some biscuits out for the plumber!

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